Assembly group with a combustion chamber shingle for a gas turbine

ABSTRACT

An assembly group for a combustion chamber of a gas turbine includes a combustion chamber shingle with a mounting element and a bolt formed as a separate structural component for supporting the combustion chamber shingle at a wall of the combustion chamber. The mounting element has a reception area into which a bolt head of the bolt is inserted transversely with respect to a longitudinal axis of the bolt and anchored therein in a form-fit manner. At the reception area, the mounting element forms an edge area that protrudes substantially radially with respect to the longitudinal axis of the bolt and that at least partially surrounds an edge of the bolt head. The edge of the bolt head does not extend exclusively in a plane that is perpendicular to the longitudinal axis of the bolt.

This application claims priority to German Patent Application No. DE102015217034.9 filed Sep. 4, 2015 and German Patent Application No. DE102015217161.2 filed Sep. 8, 2015, the entirety of both applications are incorporated by reference herein.

DESCRIPTION

The invention relates to an assembly group for a combustion chamber of a gas turbine according to the generic term of claim 1.

For the purpose of cooling, combustion chambers of a gas turbine, in particular of a gas turbine engine, have so-called combustion chamber shingles. These combustion chamber shingles are regularly provided for cladding a fire tube of the combustion chamber. Here, air for cooling down as well as for leaning the combustion and thus for reducing NOx emissions can be conducted into the combustion chamber through the combustion chamber shingle. For this purpose, the combustion chamber shingle has at least one mixed air hole. In addition, it is also provided to furnish a combustion chamber shingle with multiple, often up to several thousands, so-called effusion cooling holes via which the combustion chamber shingle is cooled against the high temperatures that are present inside the combustion. As for that, generic assembly groups are known for example from EP 0 972 992 B1 or DE 102 14 570 A1.

In practice, the individual combustion chamber shingles are fixated at a combustion chamber wall through bolts that are formed at them. The bolt of a combustion chamber shingle, which is thus formed as a stud bolt, is then fixated at the combustion chamber wall by means of a nut. In such embodiments, losses of preload due to creeping are often observed in the stud bolt. What is more, in a bolt that is formed integrally with the combustion chamber shingle, a sufficient cooling of the shingle at the location of the bolt is not easily possible. Moreover, if the combustion chamber shingle is mounted at the combustion chamber wall via an integrated bolt, it is hard to accommodate possible different requirements regarding the thermal conductivity and strength and thus the manufacturing material of the bolt and the combustion chamber shingle itself.

Thus, the invention is based on the objective to improve an assembly group for a combustion chamber of a gas turbine with at least one combustion chamber shingle that is to be mounted at a combustion chamber wall of the combustion chamber in this respect and to remedy or at least reduce the previously mentioned disadvantages.

This objective is achieved through an assembly group of claim 1 as well as through an assembly group of claim 14.

According to a first aspect of the invention, the assembly group, apart from a combustion chamber shingle and a mounting element that is formed thereat preferably integrally, also has a separate bolt for mounting the combustion chamber shingle at the combustion chamber wall of the gas turbine combustion chamber. The mounting element of the combustion chamber shingle has a reception area into which a bolt head of the bolt is inserted transversely to a longitudinal axis of the bolt and is anchored at the same in a form-fit manner. For the purpose of anchoring the bolt head in a form-fit manner, the mounting element forms an edge area that protrudes radially with respect to the longitudinal axis of the bolt at the reception area and that at least partially surrounds an edge of the bolt head. According to the invention it is now further provided that, at its bottom side that faces away from the combustion chamber shingle, the bolt head forms at least one contact surface for an abutting arrangement at the combustion chamber wall and/or at least one contact surface for an abutting arrangement at the edge area of the mounting element, extending so as to be tilted with respect to the longitudinal axis of the bolt.

Consequently, according to the first aspect of the invention, the invention is based on the basic principle that a bolt provided for mounting the combustion chamber shingle can be inserted via its bolt head in the reception area at the combustion chamber shingle and is then anchored in the same in a form-fit manner. Here, in particular the edge of the bolt head, which is surrounded by an edge area of the reception area at the combustion chamber shingle, is geometrically designed in such a manner that a defined planar abutting arrangement of the bolt head at the radially protruding edge area and/or directly at the combustion chamber wall is achieved when the combustion chamber shingle is mounted at the combustion chamber wall by means of the bolt according to the intended use. Hence, the bottom side of the bolt head has no flat, plate-shaped form, but rather differs from the same in such a manner that

-   -   a section of the bolt head can come into an abutting arrangement         at the combustion chamber wall when the combustion chamber         shingle is mounted at the combustion chamber wall, and/or     -   a section of the bolt head abuts the radially protruding edge         area of the mounting element along a contact surface that         extends in a tilted manner with respect to the longitudinal axis         of the bolt.

Thus, it has been shown that undesired bending moments and transverse forces in the bolt and in particular at the bolt head can be avoided if the bottom side of the bolt head is formed in such a manner that it is not uniformly plane and that it is not only arranged in a plate plane that extends perpendicularly to the longitudinal axis of the bolt, but if instead sections with contact surfaces are provided thereat that are tilted with respect to the longitudinal axis of the bolt and/or protrude in an elevated manner at the bottom side of the bolt head. While, thanks to the configuration of the bolt as a separated structural component, an improved cooling of the bolt can be achieved and the manufacturing material for the combustion chamber shingle can be selected by and large independently of the manufacturing material of the bolt, an optimized form-fit anchoring of the bolt at the reception area of the combustion chamber shingle as well as a longer service life of the bolt is achieved through the bolt head geometry that is provided according to the invention.

In an exemplary embodiment, formed at the edge of the bolt head are at least one first edge section, abutting the radially protruding edge area via a first contact surface, and at least one second edge section that is arranged at a distance to the first edge section and that abuts the combustion chamber wall via a second contact surface if the combustion chamber shingle is mounted at the combustion chamber wall according to the intended use. In this way, if the bolt is fixated at the combustion chamber wall, the bolt head can be supported directly against the combustion chamber wall as well as against the edge area of the mounting element that is formed at the combustion chamber shingle, wherein the edge area is also supported directly against the combustion chamber wall and for this purpose abuts the combustion chamber wall preferably in a planar manner.

The edge area of the mounting element is preferably formed in such a manner that it does not run around the entire longitudinal axis of the bolt so that the bolt head can be inserted into the reception area transversely to the longitudinal axis of the bolt. Consequently, the edge area is open towards at least one side. The second edge section of the bolt head, which forms the second contact surface for an abutting arrangement at the combustion chamber wall, is preferably present at this one open side, so that the second section is not surrounded by the radially protruding edge area, and projects into a recess that is defined by the edge area. By virtue of the fact that the preferably axially protruding edge section that comprises the second contact surface projects into a recess of the edge area at the mounting element of the combustion chamber shingle, an anti-rotation device for the bolt head can also be provided. Here, the edge section meshes in a form-fit manner into the recess, namely in such a way that any twisting of the bolt head in relation to the edge area is blocked. If a nut is screwed onto a bolt shaft of the bolt in order to fixate the combustion chamber shingle at the combustion chamber wall, the bolt is thus secured against any contortion.

In an exemplary embodiment, the bolt head is locally thickened at the at least one second edge section in the axial direction as viewed with respect to the longitudinal axis of the bolt.

A locally thickened section has an extension that is larger by at least 15% compared to adjoining sections of the bolt head. In one embodiment variant, the extension is approximately twice as large in the axial direction as the extension of adjoining sections of the bolt head or of a mean extension of the usually disc-shaped or plate-shaped bolt head. In other words, a wall thickness of the bolt head is increased at the locally thickened section by at least 15% as compared to a mean wall thickness of the bolt head in order to achieve a defined abutting arrangement of this locally thickened section at the combustion chamber wall and, where necessary, a sufficiently loadable securing against any contortion of the bolt during the further mounting of the combustion chamber shingle in the combustion chamber. In one embodiment variant, the height of the locally thickened section is increased by approximately the wall thickness of the edge area of the reception area as compared to adjoining bolt head sections.

In order to thicken the bolt head in a defined manner only in a local area, the locally thickened section of the bolt head extends along a circumference of the bolt head with a length that corresponds to at most a ⅓, preferably at most a ¼ of the total circumference of the bolt head.

Alternatively or additionally, the bolt head can be formed in a conical manner in at least one edge section that is surrounded by the edge area of the mounting element. Due to the conical extension of the edge section, a contact surface is defined that is tilted with respect to the longitudinal axis of the bolt. What is understood here by a contact surface that is tilted with respect to the longitudinal axis of the bolt is a surface that extends at an angle of more or less than 90° to a longitudinal axis of the bolt and thus obliquely to the longitudinal axis of the bolt.

In one embodiment variant, a conically shaped edge section of the bolt head becomes wider in the direction of a front side that is defined by the bolt head and that is located opposite the bottom side. Hence, such a conical edge section tapers off with respect to an axial direction along which a bolt shaft for fixating the combustion chamber shingle at the combustion chamber wall connects to the bolt head.

It has been shown in experiments and simulations that when it comes to the loads that occur at the bolt during operation, a configuration of the bolt head can be advantageous in which the bolt head is formed so as to be asymmetrical with respect to the longitudinal axis of the bolt. Here, the bolt head may for example have a base area that is formed by a rectangular surface and a semicircular surface connecting to the same, as viewed along the longitudinal axis of the bolt.

In one embodiment variant, an edge section is formed at the bolt head, with that edge section or at least its contact surface extending at least in one area so as to be tilted by an angle with respect to a connection direction along which the bolt head is inserted into the reception area of the mounting element of the combustion chamber shingle. Through the edge section that extends in a tilted manner with respect to the connection direction at least in one area and that is for example conically shaped for this purpose, the insertion of the bolt head into the reception area can be facilitated, for example. Further, it can be ensured through such a configuration of the edge section that the inserted bolt head is locked inside the reception area if it has been inserted according to the intended use.

Particularly for this purpose it can additionally be provided that the radially protruding edge area of the mounting element defines a channel for inserting the bolt head, with this channel tapering off and extending along the connection direction. At that, the taper degree of the channel can correspond to an angle at which the at least one area of the edge section extends in a tilted manner with respect to the connection direction. Thus, a clearance between the edge section and the edge area at the channel is reduced and a predefined alignment of the bolt head is ensured inside the reception area through the tapering channel at the mounting element and the obliquely extending area of the edge section at the bolt head. Furthermore, it has been shown that transverse forces acting on the bolt head during fixation of the combustion chamber shingle at the combustion chamber wall can be reduced in particular through designing the edge section of the bolt head so that it extends in a manner tilted with respect to the connection direction.

For reducing bending moments and transverse forces that occur at the bolt head, it can further be provided either alternatively or additionally that an edge section with a contact surface for abutting arrangement at the radially protruding edge area of the mounting element is formed at the bolt head, wherein this contact surface extends in a tilted manner with respect to a first spatial direction and to the longitudinal axis of the bolt as well as with respect to a second spatial direction that is perpendicular to the first spatial direction. In this way, the contact surface can for example extend so as to be tilted with respect to all three spatial directions that are perpendicular to one another. Such a configuration has proven to be advantageous in particular in combination with a bolt head that is shaped conically at its edge. Here, a first conically shaped edge section may for example be provided in a front part of the bolt head that is located in the connection direction, wherein this front part may for example have a semicircular base area with an edge that is convexly arched in the connection direction. In that case, the edge section with the contact surface that extends in a tilted manner is provided at a second, rear part of the bolt head and is inserted into the tapering channel of the mounting element, so that the tilted contact surface of the bolt head edge abuts in a planar manner to an inner surface of the channel that extends in a tilted manner due to the taper. In this way, a compensation for transverse forces and bending moments is achieved during mounting of the bolt at the combustion chamber wall, which are introduced via the front part of the bolt head and its form-fit mesh into the reception area of the mounting element.

A preferably conically shaped transitional area is provided for reducing a notch effect in the area of the transition between a bolt shaft of the bolt, via which the combustion chamber shingle is held at the combustion chamber wall, and the bolt head. The transition between the bolt shaft, which for example supports an external thread of the (thread) bolt, thus occurs along the longitudinal axis of the bolt via a conically shaped section of the bolt that consequently becomes wider in the direction of the bolt head.

It has been shown in this context that a configuration of the lateral surface of a correspondingly concavely arched transitional area with a radius of curvature in the range of 1.0 to 3.5 times the diameter of the bolt shaft is particularly advantageous for the long life fatigue strength of the bolt when it is used in a combustion chamber of a gas turbine engine.

For the purpose of solving the task at hand, it is provided according to another aspect of the invention that the bolt head that is held in a form-fit manner at the reception area of the combustion chamber shingle has a front side which is facing towards a basal plane of the reception area and at which a concave internal arching is provided that is arranged centrally with respect to a bolt shaft of the bolt. The configuration of the bolt head with a concave internal arching at its front side can of course be readily combined with a configuration of the bolt head according to the first aspect of the invention.

Through the concave internal arching, a recess is formed at the front side of the bolt head that is offset with respect to the basal plane of the reception area. Together with the basal plane, this recess defines a central air chamber in the area of the connection of the combustion chamber shingle to the bolt. Via this air chamber between the bolt head and the surface of the combustion chamber shingle in particular an improved cooling of the bolt and/or of the combustion chamber shingle by means of a cooling air flow can be achieved. Through the concave internal arching, a volume for cooling air is made available that is increased as compared to the volume of a cooling air gap as it would be defined by a planar front side of the bolt head and a planar basal plane of the reception area.

In the cross-section, the central concave internal arching can have a radius of curvature which corresponds to at least one sixth of a mean width of the bolt head in transverse direction to the longitudinal axis of the bolt. In this manner, it is achieved that the internal arching and the air chamber that is defined by it take up a substantial part of the front side of the bolt head. It can also be provided that the concave internal arching has a radius of curvature in cross-section that corresponds to at least half of the diameter of a bolt shaft of the bolt by which the combustion chamber shingle is held at the combustion chamber wall. Here, the concave internal arching is in particular preferably provided in extension of the bolt shaft at the front side of the bolt head, and is thus located below the bolt shaft in the mounted state of the combustion chamber shingle according to the intended use.

In one embodiment variant, the internal arching is delimited in cross-section by two convex bulges that protrude in the direction of the basal plane. By means of the convex bulges, a reduction of the tensions in the transitional area from the bolt shaft to the bolt head is achieved. Here, the two convex bulges that can be seen in cross-section can be formed by a collar or rim that circumferentially extends at the front side and protrudes in an elevated manner. In this case, such a protruding collar may extend in a circular-ring-shaped manner at the front side of the bolt head, for example.

Besides, it can be provided that the combustion chamber shingle, in particular the mounting element, is provided with at least one opening for a cooling air flow. Here, the at least one opening can be provided at a basal plane of the reception area and/or at a side wall of the reception area for the bolt head that is protruding therefrom. In a further development that is based hereon, multiple effusion cooling holes may for example be provided at the mounting element, in particular in the area of the basal plane.

Alternatively or additionally, the bolt can be formed with at least one passage opening or passage channel for the supply of cooling air to the bolt head and/or the combustion chamber shingle. Here, a passage opening or passage channel is formed at a bolt shaft and/or the bolt head in a preferably centric manner with respect to the longitudinal axis of the bolt.

The bolt may be manufactured as a pressed part or by means of metal powder injection molding or an additive manufacturing method such as selective laser sintering, direct laser depositioning, or by using laser deposition welding. The same principally also applies to the mounting element of the combustion chamber shingle as well as to the combustion chamber shingle itself.

Although the assembly group according to the invention can be used in gas turbines with a combustion chamber of any design, in a preferred variant the use in a gas turbine engine is provided. Here, the assembly group with the combustion chamber shingle and the bolt for bearing the combustion chamber shingle can in particular be used in a fire tube of a combustion chamber.

Other advantages and features of the invention will become apparent in the following description of exemplary embodiments by referring to the Figures.

Herein:

FIG. 1 shows a schematic sectional rendering of a gas turbine engine in which an assembly group according to the invention is used;

FIG. 2 shows a schematic sectional rendering of a combustion chamber of the gas turbine engine of FIG. 1;

FIG. 3 shows, by sections, a top view of a combustion chamber shingle that is used inside a fire tube of the combustion chamber of FIG. 2;

FIGS. 4A and 4B schematically show sectional renderings for illustrating fixations of the combustion chamber shingle to a combustion chamber wall for the fire tube as they are known in the state of the art;

FIG. 5A shows a sectional rendering of a bolt of a first embodiment variant of an assembly group according to the invention for mounting a combustion chamber shingle;

FIG. 5B shows a perspective view of a mounting element of a combustion chamber shingle of the first exemplary embodiment of an assembly group according to the invention, which forms a reception area for a bolt head of the bolt of FIG. 5A;

FIG. 6A shows, by sections, a sectional rendering of a bolt of a second embodiment variant of an assembly group according to the invention, which has a bolt head that is conically shaped at its edges;

FIG. 6B shows a sectional rendering of the mounting element for the bolt head of FIG. 6A;

FIGS. 6C to 6E show different renderings of the bolt according to the second embodiment variant;

FIG. 6F shows, by sections and in a perspective view, the mounting element of FIG. 6B with a view into the internal space of the reception area.

FIG. 1 shows a schematic sectional rendering of a gas turbine engine T, which, among other parts, has a combustion chamber section 15 with a combustion chamber that comprises an assembly group that is designed according to the invention. Otherwise, the gas turbine engine T is embodied in a per se known manner and comprises, among other parts, an air inlet 11, a fan 12 that rotates inside an engine housing, a medium-pressure compressor 13 and a high-pressure compressor 14, which are arranged behind each other along an engine axis 1. Connecting to the high-pressure compressor 14 is the combustion chamber section 15, followed by a high-pressure turbine 16, a medium-pressure turbine 17 and a low-pressure turbine 18 along the engine axis 1. From the low-pressure turbine 18, exhaust gas flows outward via an exhaust nozzle 19 at the end of the gas turbine engine T.

The medium-pressure compressor 13 and the high-pressure compressor 14 of a compressor unit of the gas turbine engine T respectively comprise multiple stages, of which each has an arrangement of fixed stationary guide vanes 20 that extend in the circumferential direction. These guide vanes 20 are often also referred to as stator blades, and they protrude radial inward from a core 21 into a ring-shaped flow channel of the compressors 13 and 14. Further, the compressors 13 and 14 have multiple compressor rotor blades 22 that protrude radially outward from a rotatable compressor drum or compressor disc 26. This compressor drum or compressor disc 26 is coupled to a turbine rotor hub 27 of a turbine unit that is formed by the high-pressure turbine 16, the medium-pressure turbine 17 and the low-pressure turbine 18. Connecting to the compressor stages of the gas turbine engine T with the medium-pressure compressor 13 and the high-pressure compressor 14, is the combustion chamber section 15 in which the driving energy for driving the turbine stages of the turbines 16, 17 and 18 is generated. Stationary guide vanes 23 are also respectively provided in turbines 16, 17 and 18. They protrude radially inward at the core 21 into a ring-shaped flow channel of the turbines 16, 17 and 18. Further, radially outwardly protruding turbine rotor blades 24 are provided at the turbine rotor hub 27.

During operation, the compressor drum or compressor disc 26 including the compressor rotor blades 22 that are attached thereat as well as the turbine rotor hub 27 including the turbine rotor blades 24 attached thereat rotate round the engine axis 1. Via a shaft 25, a torque that is thus generated at the turbine rotor blades 24 is transferred to the fan 12 in order to drive it and to suction in an air flow into the gas turbine engine 1 along an entry direction A. At that, the sucked-in air is divided in a known manner into a primary air flow and a secondary air flow, in particular in order to obtain the greater part of the total thrust from the secondary air flow. The secondary air flow is conducted externally past the core 21 inside of which the compressor 13 and 14, the combustion chamber section 15 as well as the turbines 16, 17 and 18 are arranged. A that, the secondary air flow is conducted past the core 21 along the engine axis 1 inside a bypass channel 10. By contrast, the primary air flow is conducted to the compressors 13 and 14 and subsequently into the combustion chamber of the combustion chamber section 15.

In the sectional rendering of FIG. 2, a configuration of a combustion chamber 3 of this combustion chamber section 15 is shown. Here, the combustion chamber 3 comprises, among other parts, a fuel nozzle 29 that is supported inside a combustion chamber head. Via the fuel nozzle 29, fuel is injected into a fire tube 300 of the combustion chamber 3 that defines the combustion space of the combustion chamber 3. This fire tube 300 is accommodated inside a cavity that is defined by a combustion chamber exterior housing 30 and a combustion chamber interior housing 31 of the combustion chamber 3. The exhaust gases of the mixture that is ignited inside the combustion space of the fire tube 300 reach the high-pressure turbine 16 via a turbine inlet guide vane row 33, so that the turbine stages are set into rotation. The combustion space of the fire tube 300 is delimited by a combustion chamber wall 32 of the combustion chamber 3, at which combustion chamber shingles 34 are internally arranged. Thus, the combustion chamber wall 32 encloses the combustion space of the combustion chamber 3 and supports the combustion chamber shingles 34 by which the combustion chamber wall 32 is clad so as to facilitate additional cooling and to withstand the high temperatures that are present inside the combustion space.

Here, the combustion chamber shingles 34 are respectively supported at the combustion chamber wall 32 by one or multiple bolts 4. Here, each bolt 4 extend through an opening at the combustion chamber wall 32 and is fixated at the combustion chamber wall 32 by means of one nut 6, respectively. Cooling of the respective combustion chamber shingle 34 is facilitated through multiple effusion cooling holes 340 that are provided at the combustion chamber shingle 34 according to FIG. 3. In addition, a combustion chamber shingle 34 can have at least one admixing hole 35 via which air can flow into the combustion space from an exterior space that surrounds the fire tube 300. Here, the air that flows through an admixing hole 35 serves for cooling down and/or the leaning the combustion.

At that, the exterior space that surrounds the fire tube 300, for example in the form of an annular channel, forms an air supply 36 for the admixing holes 35 and the effusion cooling holes 340. Air that flows into the combustion chamber 3 along an inflow direction Z is divided in the area of the fuel nozzle 29 through a cup-shaped section into a primary air flow for the combustion space of the fire tube 300 and a secondary air flow for the exterior space including the air supply 36 that surrounds the fire tube 300. Here, the air usually flows into the combustion chamber 3 via a diffusor (not shown in FIG. 2).

So far, the fixation of the combustion chamber shingle 34 at the combustion chamber outside wall 32 has been regularly carried out by means of bolts 4 that are formed integrally with a combustion chamber shingle 34, as is illustrated in an exemplary manner in a sectional rendering in FIGS. 4A and 4B. Here, a bolt shaft 40 of a bolt 4 that is formed at the inner side of the combustion chamber shingle 34 has a thread 42 at its top end. With the bolt shaft 40 extending through an opening in the combustion chamber wall 32 and being screwed on from the outside onto a nut 6, the combustion chamber shingle 34 is mounted at the combustion chamber wall 32 according to the intended use, so that it is internally supported against the combustion chamber wall 32 through a support 341 of the combustion chamber shingle 34.

The manufacture of a combustion chamber shingle 34 is usually carried out particularly by means of casting and applying a ceramic coating, or through an additive manufacturing method, such as for example selective laser sintering, direct laser depositioning, or by means of electron beam weld cladding. However, a bolt 4 that is formed integrally at the combustion chamber shingle 34 renders particularly manufacture by means of additive manufacturing methods more difficult. Moreover, problems due to creeping of the material are often observed during operation, which can lead to a failure of the bolt 4 and thus to a loss of the combustion chamber shingle 34. The solution according to the invention provides a remedy for this problem, with exemplary embodiments of the invention being described in the following in more detail by referring to FIGS. 5A to 5B and 6A to 6F.

What both variants of FIGS. 5A to 5B and 6A to 6F have in common is that the bolt 4 is formed as a separate structural component and is inserted into a reception area 50 of a mounting element 5 at the combustion chamber shingle 34 and is anchored therein in a form-fit manner. Here, the bolt 4 respectively forms a disc-shaped bolt head 41 that can be inserted into the reception area 50 at the combustion chamber shingle 34 along a connection direction V, that extends transverse to a longitudinal axis of the bolt M. For this purpose, the reception area 50 of the mounting element 5 that is formed in one piece at the combustion chamber shingle 34 is formed in a pouch-shaped manner and is open towards a transverse side, so that the bolt head 41 of a bolt 4 can be inserted into it along the connection direction V and can be supported in a form-fit manner inside the reception area 50. Here, in order to secure the bolt head 41 at the reception area 50 in a form-fit manner, the mounting element 5 forms substantially radially protruding, web-shaped edge areas 51, surrounding the bolt head 41 that is inserted into the reception area 50 at the edge side.

In the exemplary embodiment of FIGS. 5A and 5B, the bolt head 41 is formed in a disc-shaped manner and so as to be asymmetrical with respect to the longitudinal axis of the bolt M. The bolt head 41 has a semicircular base area at a front part, as viewed in the connection direction V, while a rear part of the bolt head 41, at which the bolt shaft 40 protrudes, has a rectangular base area.

At its rear part, the disc-shaped bolt head 41 is provided with a superstructure 46, which defines a local thickening of an edge section of the bolt head 41 at a bottom side of the bolt head 41. Through this superstructure 46, a wall thickness of the bolt head 41 is locally increased and namely in an area in which the edge of the bolt head 41 is not surrounded by the radially protruding edge area 51 of the mounting element 5 and can internally abut at the edge area 51 via (first) contact surfaces. Thus, the superstructure 46 is provided at a rear part of the bolt head 41 with respect to the connection direction V, which is present at the open side of the pouch-shaped reception area 50 if the bolt 4 is inserted therein according to the intended use. Here, the height of the superstructures 46 is dimensioned in such a manner that the superstructure 46 is flush with the edge area 51 of the mounting element 5 and thus the bolt head 41 can directly abut at the combustion chamber wall 32 via a (second) contact surface 460 if the nut 6 is screwed onto the bolt shaft 40 in order to fixate the combustion chamber shingle 34 at the combustion chamber wall 32. Thus, on the one hand, the bolt head 41 can directly locally abut at the combustion chamber wall 32 via the superstructure 46 and, on the other hand, can be supported at the edge area 51 of the mounting element 5 in the present case along more than 60%, e.g. approximately 70% to 80%, of its total circumference. In the present case, the superstructure 46 has approximately the same thickness as the edge area 51.

If mounted at the combustion chamber wall 32 according to the intended use, the edge area 51, which is U-shaped in top view, as well as the superstructure 46 respectively abut in a planar manner at the combustion chamber wall 32. In this manner, it is avoided that the bolt head 41 is too tightly wound inside the reception area 50 as the nut 6 is being tightened, and that it becomes subject to undesired bending moments in the course of the mounting process, which ultimately lead to a failure of the bolt 4 during operation of the gas turbine engine T. Through the superstructure 46 at the bolt head 41, the bolt 4 is further also secured against any twisting relative to the mounting element 5, if the bolt head 41 is inserted into the reception area 50. For this purpose, the superstructure 46 is embodied with such a width that is surrounded by the radially protruding edge areas 51 of the mounting element 5 that are located transversely opposite with respect to the longitudinal axis of the bolt M. Consequently, the superstructure 46 abuts the edge area 51 or at least comes into an abutting arrangement with the same at opposite positions transversely to the longitudinal axis of the bolt M in order to block any twisting of the bolt 4 around the longitudinal axis of the bolt M. In this manner, the bolt 4 remains in a defined position relative to the combustion chamber shingle 34 if it is mounted at the combustion chamber wall 32 and the nut 6 is screwed to the bolt shaft 40. Thus, an anti-rotation device is integrally formed at the bolt head 41 through the superstructure 46.

Further, the reception area 50 has a basal plane 500 above which the edge area 51 of the mounting element 5, which is protruding substantially in the radial direction and extending partially along the circumference of the longitudinal axis of the bolt M, extends. This basal plane 500 at the surface of the combustion chamber shingle 34 is faced by a front side 410 of the bolt head 41 when the bolt head 41 is inserted into the reception area 50 according to the intended use. In order to provide an air chamber with a comparatively large volume for the through-flow of cooling air between the front side 410 and the basal plane 500, the front side 410 is not embodied in a planar manner, but rather has a concave internal arching 43 that is preferably arranged centrally with respect to the bolt shaft 40. The concave internal arching 42 has an inner radius that substantially corresponds to the radius of the circular cylindrical bolt shaft 40.

The concave internal arching 43 is rimmed by a collar that is formed in the manner of a circular-ring and protrudes in an elevated manner at the front side 410. Extending from this collar at the front side 410 of the bolt head 41, two convex bulges 44, which are arranged at a distance from each other in the transverse direction with respect to the longitudinal axis of the bolt M, can be seen in the sectional rendering of FIG. 5A. The collar that surrounds the concave internal arching 43 is thus formed in a bead-like manner. Connecting to this collar in the radial direction or transverse direction is respectively one outer edge 45 of the bolt head 41. In this way, the bead-like collar surrounding the concave internal arching 43 is arranged at a distance to the outermost edge 45 of the bolt head 41 in the radial direction. Through the bead-shaped collar at the front side of the bolt head 41 tensions occurring in a transitional area 411 between the bolt shaft 40 and the bolt head 41 are reduced. Here, the thickness of the collar is dimensioned in such a way that a gap for cooling air still remains between this collar and the basal plane 500 if the bolt head 41 is inserted into the reception area 50 according to the intended use and the combustion chamber shingle 34 is mounted according to the intended use.

Further, a recess 501 is provided at a side wall of the reception area 50 that is protruding in the axial direction for the purpose of providing a cooling air flow to the combustion chamber shingle 34. Via the recess 501, a cooling air flow can be guided to an external side of the combustion chamber shingle 34 that is facing away from the combustion space. This cooling air flow can for example be guided to the mounting element 5 through a passage channel (not shown in FIG. 5A) that is formed inside the bolt shaft 40 (cf. also FIG. 6D).

Further, the bolt 4 of the embodiment variant of FIGS. 5A and 5B (as well as the bolt 4 of the variant of FIGS. 6A to 6F) is optimized in the area of the transition between the bolt shaft 40 and the bolt head 41, so that no increased risk of failure due to a possible notch effect is present in this area. Thus, a conically shaped transitional area 411 is provided between the bolt shaft 40 and the bolt head 41. This conical transitional area 410 has a concave arching with a radius of curvature R40. In the present case, this radius of curvature R40 substantially corresponds to the radius of the circular cylindrical bolt shaft 40. However, the shape-optimized transitional area 410 may have a contour that deviates from the shape of a circular ring.

In the further exemplary embodiment according to the FIGS. 6A to 6F, a design of the bolt head 41 as well as of the reception area 50 at the combustion chamber shingle 34 has been chosen that differs from the variant of the FIGS. 5A and 5B. As can in particular be seen from the sectional renderings of the bolt head 41 and the mounting element 5 in the FIGS. 6A and 6B, in this case the edge of the bolt head 41, which is surrounded in a form-fit manner inside the reception area 50 by the edge area 51 of the mounting element 5, has a conical shape. Accordingly, the edge of the bolt head 41 continuously becomes wider in the direction of its front side 41 or tapers off in the direction of the bolt shaft 40. Correspondingly, the edge area 51 of the mounting element 5 forms conically extending contact surfaces for an abutting arrangement of the edge of the bolt head 41 that is surrounded by it. Thus, the edges of the bolt head 41 that are provided for the form-fit anchoring of the bolt 4 at the mounting element 5 form contact surfaces that do not only extend in a flat plane that is perpendicular to the longitudinal axis of the bolt M. Rather, the contact surfaces of the bolt head 41 that are provided for the abutting arrangement at the edge area 51 of the mounting element 5 are formed so as to be tilted with respect to the longitudinal axis of the bolt M, and namely so as to be tilted in the direction of the basal plane 500 of the reception area 50.

Further, as compared to the embodiment variant of FIGS. 5A and 5B, the bolt head 41 has an enlarged concave internal arching 43 at its front side 410 that is facing towards the basal plane 500. Thus, here the internal arching 43 spans almost the entire width of the bolt head 41 in the cross-section. For example, a radius of curvature R43 of the concave internal arching is more than twice as large as the radius of the circular cylindrical bolt shaft 40. In this manner, a comparatively narrow support 41 is achieved at the basal plane 500 of the reception area 50 in combination with the conical configuration of the edge of the bolt head 41. In addition, in this way the bolt head 41 is aligned inside the reception area 50 already during insertion, so that the bolt head 41 abuts at the edge area 51 of the mounting element 5 in a planar manner in particular after the combustion chamber shingle 34 has been mounted at the combustion chamber wall 32. In this manner, a self-centering of the bolt head 41 inside the reception area 50 is achieved by means of the conical design of the edge of the bolt head 41 if the bolt head 41 is inserted into the reception area 50 along the connection direction V and thus transversely to the longitudinal axis of the bolt.

For optimizing the force path and for reducing undesired transverse forces and bending moments, the shape of the reception area 50 and of the edge area 51 of the mounting element 5 are also embodied in an alternative manner. Thus, the edge area has concave and convex areas that transition into each other and have approximately corresponding radiuses r_(a), r_(i). Further, the substantially radially protruding edge areas 51 of the mounting element 5 have a wall thickness d1, d2 that changes starting from the basal plane 500. Here, a wall thickness d2 of the edge area 51 is increased in the area of the abutting arrangement of the conical edge of the bolt head 41 as compared to a wall thickness d1 in an area that is located near the basal planes 500, so that a higher strength is ensured.

As can in particular be seen from FIGS. 6D and 6E, in the shown exemplary embodiment the bolt head 41 is formed with a base area that is formed by a rectangular shape with a semicircle connecting thereto. Here, the semicircle with a radius Ra is present at a front side of the bolt head 41 in the connection direction V, which is completely surrounded by the edge area 51 of the mounting element 5 if the bolt head 41 is inserted into the pouch-shaped reception area 50 according to the intended use. The radius Ra of the front semicircle of the base area corresponds to half the width b of the rectangular shape. Here, the end of the bolt head 41 that is defined by the semicircular base area and is located in the connection direction V is embodied in an overhanging manner with respect to the rear end with the rectangular base area by means of an off-set arrangement of the center point of the front semicircle with respect to the longitudinal axis of the bolt M in connection direction V. Further, the length a of the rectangular shape that extends along the connection direction V is smaller than its width b and the radius Ra of the semicircle.

The individual parts of the base area of the bolt head 41 define different edge sections 41 a and 41 b that are surrounded by the edge area 51 of the mounting element 5 when the bolt head 41 is inserted and internally abut at the edge area 51 via the contact surfaces 412 when the combustion chamber shingle 34 is mounted at the combustion chamber wall 32. While a first edge section 41 a is formed along a circle line at the front side of the bolt head 41, the edge sections 41 b with the length a extend along the connection direction V. Thanks to the asymmetric configuration of the bolt head 41 with respect to the longitudinal axis of the bolt M that is thus created, the bolt head 41 that is inserted into the reception area 50 is secured against any twisting around the longitudinal axis of the bolt M if the nut 6 is screwed on.

In the present case, the two edge sections 41 b of the bolt head 41, which extend along the connection direction V, are respectively divided into two partial areas 41 ba and 41 bb. The partial area 41 bb is located between the partial area 41 ba and the front edge section 41 a. This partial area 41 bb is formed conically and so as to become wider towards the front side of the bolt head 41. In addition, the rear partial area 41 ba, as viewed in the connection direction V, is tilted with respect to the connection direction V by an angle α₄. Thus, in the partial area 41 ba, the edge section 41 b forms a contact surface 412 for abutting arrangement at the substantially radially protruding edge area 51 of the mounting element 5, with the contact surface 412 extending in a tilted manner with respect to a first spatial direction x that coincides with the connection direction V and the longitudinal axis of the bolt M, as well as extending in a tilted manner with respect to a second spatial direction y that is perpendicular to the first spatial direction x and the connection direction V. This complex design of the edge section 41 b at the partial area 41 ba, which is illustrated particularly with a view to FIG. 6C, at least partially compensates the conical shape at the front side of the bolt head 41 in order to reduce transverse forces that are acting on the bolt head 41 as a result of the fixation at the combustion chamber wall 32.

Further, a channel corresponding to the geometry of the partial area 41 ba is formed at the edge area 51 of the mounting element 5. This channel tapers off reversely to the connection direction V, or becomes wider in the connection direction V, and thus ensures a defined planar abutting arrangement at the edge area 51 of the contact surface 412 of the partial area 41 ba which extends transversely in two respects if the bolt head 41 is inserted into the reception area 50. For the purpose of configuring the channel that tapers off reversely to the connection direction V, the edge area 51 has areas 51 a, 51 b that are protruding in a web-like manner and have a wall thickness that continuously diminishes along the connection direction V from a maximum value d3 to a minimum value d4. Due to the continuously changing wall thickness, the rear section of the channel, as viewed in the connection direction V, extends at an angle α₅ with respect to the connection direction V, wherein this angle α₅ substantially corresponds to the angle α₄ at the rear partial area 41 ba of the bolt head 41. Thus, those areas of the edge area 51 that connect to each other along the connection direction V and protrude in a web-like manner on the one hand have a changing wall thickness in a rear part for defining the expanding channel and for surrounding of the back or rear edge section 41 b of the bolt head 41, and on the other hand have a constant wall thickness d4 in a front part for surrounding the front edge section 41 a of the bolt head 41.

In this way, by virtue of the interaction of the edge area 51 and the channel which is defined by it and into which an edge of the bolt head 41 is inserted, namely with the edge section 41 b of the bolt head 41 that forms contact surfaces 412 that are oriented differently with respect to the connection direction V, not only a centering of the bolt head 41 inside the reception area 50 during insertion of the bolt head 41 is achieved, but in this way also a defined alignment of the bolt head 41 in the axial direction and a defined abutting arrangement at an inner side of the edge area 51 of the mounting element 5, which is not completely circumferential, is obtained if the combustion chamber shingle 34 is fixedly attached at the combustion chamber wall 32 by means of the bolt 4.

Although this is not shown in 6A to 6F, here, too, it can be provided in a further development that the bolt head 41 has a local thickening at an area of its edge that is located in the rear with respect to the connection direction V, so as to further reduce a bending moment that occurs during mounting and to provide additional securing against any contortion of the bolt 4 during the attachment of the nut 6.

Further, alternatively or additionally also a bolt washer with a conical contact surface can be provided for the recovery of lost bolt pretension due to creeping. Such a bolt washer is fit onto the bolt shaft 40 and is arranged between the nut 6 and the combustion chamber wall 32 after the combustion chamber shingle 34 has been fixated.

As is indicated in an exemplary manner in FIG. 6D, the bolt shaft can have a passage channel 400 for cooling air that is arranged centrally inside the bolt shaft. Via this passage channel 400, the cooling air can then flow via the bolt shaft 400 into the air chamber that is defined with the concave internal arching 43 d and thus in particular to the bolt head 41 and the combustion chamber shingle 34. Alternatively or additionally, the pouch-shaped reception area 50 can have cooling air openings at its side walls.

Particularly the bolt 4, which can be inserted into the respective reception area 50 of the combustion chamber shingle 34 as a separate structural component, can be manufactured by means of selective laser sintering, direct laser depositioning, by means of electron beam weld cladding, as a pressed part or through metal powder injection molding. The same principally also applies to the mounting element 5 of the combustion chamber shingle 34 as well as to the combustion chamber shingle 34 itself. Thanks to the at least two-part superstructure, it is possible to manufacture the bolt 4 and the combustion chamber shingle 34 separately from each other. In this way, it is also possible to choose independently of each other the materials for the combustion chamber shingle 34 on the one hand and the bolt 4 that is used to mount the combustion chamber shingle 34 at the combustion chamber wall 32 on the other hand. Particularly by embodying the bolt head 41 with the geometry according to the invention, the form-fit connection between the bolt head 41 and the combustion chamber shingle 34 is optimized in a targeted manner, so that for example undesired bending moments and transverse forces acting onto the bolt head 41 during the fixation of the combustion chamber shingle 34 at the combustion chamber wall 32 can be considerably reduced or even completely avoided as compared to solutions known to date. Here, it is of course possible to fixate the combustion chamber shingle 34 at the combustion chamber wall 32 by means of multiple (at least two) separate bolts 4, for which purpose it would have multiple mounting elements 5 that, where necessary, can also be oriented differently with respect to each other.

PARTS LIST

-   1 engine axis -   10 bypass channel -   11 air inlet -   12 fan -   13 medium-pressure compressor -   14 high-pressure compressor -   15 combustion chamber section -   16 high-pressure turbine -   17 medium-pressure turbine -   18 low-pressure turbine -   19 exhaust nozzle -   20 guide vane -   21 core -   22 compressor rotor blade -   23 guide vane -   24 turbine blade -   25 shaft -   26 compressor drum or compressor disc -   27 turbine rotor hub -   28 outlet cone -   29 fuel nozzle -   3 combustion chamber -   30 combustion chamber exterior housing -   300 fire tube -   31 combustion chamber interior housing -   32 combustion chamber wall -   33 turbine inlet guide vane row -   34 combustion chamber shingle -   340 effusion cooling hole -   341 support -   35 admixing hole -   36 air supply -   4 bolt -   40 bolt shaft -   400 passage channel -   41 bolt head -   410 front side -   411 transitional area -   412 contact surface -   41 a, 41 b edge section -   41 ba, 41 bb partial area -   42 thread -   43 internal arching -   44 bulge -   45 outer edge -   46 superstructure (locally thickened edge section) -   460 contact surface -   5 mounting element -   50 reception area -   500 basal plane -   501 recess -   51 edge area -   51 a, 51 b area protruding in a web-like manner -   6 nut -   A entry direction -   a, b length -   d1, d2, d3, d4 wall thickness -   M longitudinal axis of the bolt -   R40, R41, R43 radius of curvature -   Ra radius -   r_(a), r_(i) radius -   T gas turbine engine -   V connection direction -   Z inflow direction -   α₄, α₅ angle 

1. Assembly group for a combustion chamber of a gas turbine, comprising: one combustion chamber shingle with a mounting element, and at least one bolt formed as a separate structural component for mounting the combustion chamber shingle at a combustion chamber wall of the combustion chamber, wherein the mounting element has a reception area into which a bolt head of the bolt is inserted transversely with respect to a longitudinal axis of the bolt and anchored therein in a form-fit manner, at the reception area, the mounting element forms an edge area that protrudes substantially radially with respect to the longitudinal axis of the bolt and surrounds the edge of the bolt head at least partially, and at its bottom side that is facing away from the combustion chamber shingle, the bolt head that is inserted into the reception area forms at least one contact surface for an abutting arrangement at the combustion chamber wall and/or at least one contact surface for an abutting arrangement at the edge area of the mounting element, with the contact surface extending in a tilted manner with respect to the longitudinal axis of the bolt.
 2. Assembly group according to claim 1, wherein at least one first edge section is formed at the edge of the bolt head, abutting at the radially protruding edge area, and at least one second edge section that is arranged at a distance to the first edge section is formed at the edge of the bolt head, abutting at the combustion chamber wall if the combustion chamber shingle is mounted thereat according to the intended use.
 3. Assembly group according to claim 2, wherein the edge area of the mounting element is embodied so as to not extend along the entire circumference of the longitudinal axis of the bolt and so as to be open towards at least one side, and in that the second edge section of the bolt head is present at this one side, so that the second section is not surrounded by the radially protruding edge area.
 4. Assembly group according to claim 2, wherein the bolt head is locally thickened at the second edge section in the axial direction with respect to the longitudinal axis of the bolt.
 5. Assembly group according to claim 4, wherein a locally thickened section has an extension in the axial direction that is increased by 15% and up to 100% as compared to adjoining sections of the bolt head.
 6. Assembly group according to claim 4, wherein a locally thickened section of the bolt head extends along a circumference with a length that corresponds to at most a ⅓ of the total circumference of the bolt head.
 7. Assembly group according to claim 1, wherein the bolt head is conically shaped at an edge section that is surrounded by the radially protruding edge area of the mounting element.
 8. Assembly group according to claim 7, wherein a conically shaped edge section of the bolt head becomes wider in the direction of a front side that is defined by the bolt head.
 9. Assembly group according to claim 1, wherein an edge section is formed at the bolt head, which at least in one area extends so as to be tilted at an angle (α₄) with respect to a connection direction along which the bolt head is inserted into the reception area of the mounting element of the combustion chamber shingle.
 10. Assembly group according to claim 9, wherein the radially protruding edge area of the mounting element defines a channel for inserting the bolt head that tapers off and extends along the connection direction, wherein the taper degree of the channel corresponds to the angle (α₄) at which the at least one area of the edge section extends in manner tilted with respect to the connection direction.
 11. Assembly group according to claim 1, wherein an edge section with a contact surface for abutting arrangement at the radially protruding edge area of the mounting element is formed at the bolt head, wherein the contact surface extends in a tilted manner with respect to a first spatial direction and the longitudinal axis of the bolt, as well as with respect to a second spatial direction that is perpendicular to the first spatial direction.
 12. Assembly group according to claim 1, wherein a conical transitional area is formed between a bolt shaft of the bolt by means of which the combustion chamber shingle is supported at the combustion chamber wall and the bolt head.
 13. Assembly group according to claim 12, wherein a lateral surface of the transitional area is concavely arched and has a radius of curvature that corresponds to the range of 1.0 to 3.5 times the diameter of the bolt shaft.
 14. Assembly group for a combustion chamber of a gas turbine, comprising: one combustion chamber shingle with a mounting element and at least one bolt that serves for mounting the combustion chamber shingle at a combustion chamber wall of the combustion chamber and that is formed as a separate structural component, wherein the bolt has a bolt shaft by means of which the combustion chamber shingle is supported at the combustion chamber wall, characterized in that the mounting element has a reception area into which a bolt head of the bolt is inserted transversely with respect to a longitudinal axis of the bolt and anchored therein in a form-fit manner, at the reception area, the mounting element forms an edge area that is substantially radially protruding with respect to the longitudinal axis of the bolt and that at least partially surrounds the edge of the bolt head, the reception area has a basal plane, above which the radially protruding edge area extends, and the bolt head has a front side which is facing towards a basal plane and at which a concave internal arching is provided that is arranged centrally with respect to the bolt shaft, in cross-section the concave internal arching has a radius of curvature that corresponds to at least a sixth of a mean width of the bolt head transversely with respect to the longitudinal axis of the bolt, in cross-section the concave internal arching has a radius of curvature that corresponds to at least half the diameter of a bolt shaft of the bolt by which the combustion chamber shingle is supported at the combustion chamber wall.
 15. Assembly group according to claim 14, wherein in cross-section the internal arching is delimited by two convex bulges that protrude in the direction of the basal plane.
 16. Gas turbine engine with a combustion chamber that comprises at least one assembly group according to claim
 1. 